TGFB1 and neoplasm: Second, we showed that the inhibition of TGF-β negatively impacts the functionality of CD8+ CTLs, as the Winn assay (essentially an in vivo test of CD8+ T cell functionality) demonstrated a reduced anti-tumor response with an equivalent number of CD8+ T cells from mice pretreated with sTGF-βR compared to control animals pretreated with IgG2a (Figure 4).